A storage subsystem is a device providing storage areas of data processed by application software operating in host computers (hereinafter abbreviated as hosts) such as servers and general purpose computers. The storage subsystem is provided with a large number of physical storage devices, and a control unit generating logical storage areas from the physical storage areas provided by the physical storage devices and controlling data input/output processing between the logical storage areas and the hosts. The physical storage devices can be 2.5-inch or 3.5-inch HDDs (Hard Disk Drives), for example.
In the control unit of the storage subsystem, electronic components such as MPUs (Micro Processor Units) for executing various control programs to execute the data input and output processing at high speed, memories for storing various data and programs, and communication interfaces for communicating with external devices and the like are formed on multiple circuit boards. Further, the storage subsystem includes a power supply for supplying power to the electronic circuits on the circuit boards and the HDDs, and a battery for supplying auxiliary power for saving data when power shutdown such as power failure occurs.
Recently, along with the increase of data storage capacity or the upgrading of the data input and output processing, the electronic circuit components are mounted with higher density on the circuit boards, the number of circuit boards being installed is increased, and high-speed MPUs are adopted, so that the amount of heat generated from the circuit boards stored in the storage control unit tends to be increased, so that there is a strong demand for a configuration capable of effectively cooling the circuit boards and components mounted thereon. A configuration is also known where the control unit, the physical storage device, the power supply and the battery are stored highly densely in a single chassis, and a plurality of such chassis are used to form a single storage subsystem.
For example, Patent Literature 1 discloses a technique for effectively cooling surface mounted components of such devices. Patent Literature 1 teaches a cooling structure of a heating body such as a CPU (Central Processing Unit) mounted on a printed board, the structure including a heat sink arranged to an upper portion of the heating body, and a cover covering the circumference of the heat sink, wherein cooling fans are arranged at both ends of a wind tunnel defined by the printed board and the cover to supply outer air into the wind tunnel and thereby cool the heating body.